共查询到14条相似文献,搜索用时 250 毫秒
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分别采用有限元法(FEM)和合乎使用(FFS)规范ASMEⅪ附录G,API 579,RCC-MRx中的影响函数法计算了断裂力学参数,求解了不同工作载荷和不同裂纹尺寸下的反应堆压力容器接管区角裂纹应力强度因子(SIF),对比了不同方法中SIF计算结果的差异,并讨论了采用不同合乎使用规范进行工程结构断裂参量计算的适用性。结果表明,对于裂纹前缘最深点应力强度因子的计算,随着裂纹尺寸的增加,基于API 579和方法2的SIF结果由不保守约10.00%逐渐变化为保守约10.00%;RCC-MRx方法的保守度为12.50%和20.00%之间;ASME方法1的SIF结果的不保守度逐渐增大,最大不保守程度可达到15.00%左右。对于裂纹前缘SIF最大值的计算,API 579,ASME方法1和ASME方法2的不保守度可接近20.00%;ASME方法2比其他3种方法的不保守度更大,最高可达34.65%。现有的FFS规范方法不适用于计算接管区角裂纹前缘的最大值,需要发展新的计算方法或公式。 相似文献
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含多局部减薄缺陷压力管道的安全评定方法讨论 总被引:2,自引:0,他引:2
局部减薄是压力管道常见的一种体积型缺陷,在管道的服役过程中不仅会出现单个局部减薄缺陷,甚至会有多个局部减薄缺陷。通过有限元方法模拟内压作用下含双局部减薄缺陷管道获得其极限载荷,讨论了在不同的轴向和环向排列方式以及不同的局部减薄相对深度下,两局部减薄缺陷间的距离对压力管道极限载荷影响程度的差异。然后对所计算模型应用API 579-1 ASMEFFS-1—2007《适合服役》与GB/T19624—2004《在用含缺陷压力容器安全评定》中对多局部减薄(凹坑)处理方法进行评定,并与有限元得到的结果进行比较,发现两评定规范既存在着保守性,也存在着不安全性。最后对两评定规范所论述的方法进行修正,提出了一种新的用于内压作用下含多局部减薄缺陷管道的多局部减薄处理方法。 相似文献
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采用分析设计评价尿素合成塔上封头腐蚀凹坑的安全性 总被引:1,自引:3,他引:1
运用有限元方法研究某厂尿素合成塔上土封头腐蚀凹抗的弹性应力分布与应力集中系数,并用分析设计方法对直径540mm,深度45mm的球缺形凹坑进行了强度校核,其结果是安全的。 相似文献
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通过SY/T6477-2000与API579-2000中含体积型缺陷管道评定方法的比较,找出两者差异对其加以分析,并对这些方面提出一些建议,有效防止使用标准时造成差错,为今后的标准编制提供参考。 相似文献
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Ihn Nanigung Seung Ha Jeong Dae Hee Lee Taek Sang Choi 《Journal of Mechanical Science and Technology》2005,19(1):51-60
The KSNP+ RV closure head drop analysis was carried out to assess the reactor core coolability in case of the RV closure head drop
accident during the refueling operation. The analysis consists of a number of different RV head drop scenarios as the postulated
accident events during refueling that include a concentric head drop case and three different cases of laterally offset head
drop cases. The analysis was initiated due to the adoption of the IHA (Integrated Head Assembly) in the KSNP+ reactor design, which increases the weight of the RV closure head assembly. Four different analysis models were developed
that correspond to the RV head drop analysis scenarios. An in-house dynamic analysis code was used for the RV head drop analysis.
The entire reactor internals and fuel assemblies are modeled by using lumped masses and spring elements. Because of the extreme
load exerted by RV head drop, most members experience stresses that are beyond the elastic limits. A separate elastic—plastic
analysis for some members was carried out and the resulting load-deflection curve was used as the stiffness of the element.
The effect of water above the reactor vessel in the refueling pool was ignored for the conservative estimation of the analysis.
The analysis shows that the concentric head drop is the most severe case of loading condition. It also reveals that the local
deformation of some reactor internals and the fuel assemblies is occurred; however the primary membrane stresses are within
the bound of allowable stress limits. Consequently the reactor core remains in coolable state. 相似文献